Electronic ic device comprising integrated optical and electronic circuit component and fabrication method

ABSTRACT

A first circuit structure of an electronic IC device includes comprises light-sensitive optical circuit components. A second circuit structure of the electronic IC device includes an electronic circuit component and an electrically-conductive layer extending between and at a distance from the optical circuit components and the electronic circuit component. Electrical connections link the optical circuit components and the electronic circuit component. These electrical connections are formed in holes which pass through dielectric layers and the intermediate conductive layer. Electrical insulation rings between the electrical connections and the conductive layer are provided which surround the electrical connections and have a thickness equal to a thickness of the conductive layer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of United States Application for patentSer. No. 17/015,634, filed Sep. 9, 2020, which claims the prioritybenefit of French Application for Patent No. 1909937, filed on Sep. 10,2019, the contents of which are hereby incorporated by reference intheir entireties to the maximum extent allowable by law.

TECHNICAL FIELD

The present invention relates to the field of microelectronics and, moreparticularly, to the field of the electronic integrated circuit devicesor electronic integrated circuit chips which comprise externallight-sensitive integrated optical circuit components, forming pixelzones, and integrated electronic circuit component such as transistorsgenerally situated under the optical circuit components.

BACKGROUND

There is a difficulty in including and making coexist electricalconnections, linking the optical circuit components and the electroniccircuit component, and a layer made of an electrically-conductivematerial or ground plane, so as to effectively prevent a couplingcapacitance between the optical circuit components and the electroniccircuit component.

SUMMARY

According to one embodiment, an electronic IC device comprises: a firstcircuit structure comprising light-sensitive optical circuit components;a second circuit structure comprising electronic circuit component andan electrically-conductive layer extending between and at a distancefrom the optical circuit components and the electronic circuitcomponent; electrical connections configured to link the optical circuitcomponents and the electronic circuit component and formed in holeswhich pass through dielectric layers and the conductive layer, andelectrical insulation rings between the conductive layer and theelectrical connections and formed around the electrical connections andin the thickness of the conductive layer.

Thus, the conductive layer can extend to close to the electricalconnections and the electrical insulation rings can be reduced, so thatany coupling capacitance between the optical circuit components and theelectronic circuit component can be avoided.

The electrical insulation rings can be composed of portions of theconductive layer, rendered dielectric.

The conductive layer can be made of doped polysilicon and the electricalinsulation rings can be made of oxidized doped polysilicon.

The first circuit structure can comprise, in succession, between anouter rear face and a front mounting face, a substrate layer provided onthe side of the mounting face with said optical circuit components and adielectric layer.

The second circuit structure can comprise, in succession, from amounting face attached to the mounting face of the first circuitstructure, a first dielectric layer including said conductive layer, alocal substrate layer provided with said electronic circuit componentand having through-openings and a second dielectric layer comprisingparts filling these through-openings.

Said electrical connections can be formed in holes which pass throughthe dielectric layers of the second circuit structure, by passingthrough the openings of the substrate layer of this second circuitstructure and at a distance from the edges of these openings, theconductive layer and the dielectric layer of the first circuitstructure, to electrical contacts of the optical circuit components ofthe first circuit structure.

The electronic IC device can comprise electrical connections formed inholes which pass through the second dielectric layer of the secondcircuit structure, to electrical contacts of the electronic circuitcomponent of the second circuit structure.

The electronic IC device can comprise an additional dielectric layerincluding a network of electrical connections selectively linking saidelectrical connections and outer electrical contacts formed in a face ofthe additional dielectric layer opposite said second dielectric layer.

The electronic IC device can comprise a third circuit structure attachedto the second circuit structure and including electronic circuitcomponent linked to said network of electrical connections.

There is also proposed a method for fabricating an electronic IC device,which comprises: fabricating a first circuit structure comprising, insuccession, between an outer face and a mounting face, a substrate layerprovided on the side of the mounting face with light-sensitive opticalcircuit components and a dielectric layer; fabricating, separately fromthe first circuit structure, a part of a second circuit structurecomprising, in succession, between a mounting face, a first dielectriclayer including an intermediate electrically-conductive layer, and alocal substrate layer; assembling the first circuit structure and saidpart of the second circuit structure by attaching the mounting face ofthe first circuit structure and the mounting face of the second circuitstructure; producing electronic circuit component on the substrate layerof the second circuit structure and through-openings through thissubstrate layer; producing a second dielectric layer above the substratelayer of the second circuit structure, this second layer filling saidopenings to the first dielectric layer; producing holes through thedielectric layers of the second circuit structure, by passing throughthe openings of the substrate layer of this second circuit structure andat a distance from the edges of these openings, the conductive layer andthe dielectric layer of the first circuit structure, to electricalcontacts of the optical circuit components of the first circuitstructure; producing electrical insulation rings by a transformation ofportions of the conductive layer, adjacent to the holes, via said holes;and filling said holes with an electrically-conductive material so as toform electrical connections linked to the electrical contacts of theoptical circuit components of the first circuit structure.

The method can comprise: producing holes through the second dielectriclayer of the second circuit structure to electrical contacts of theelectronic circuit component; and filling these holes with anelectrically-conductive material so as to form electrical connectionslinked to the electrical contacts of the electronic circuit component ofthe second circuit structure.

The method can comprise: producing, above the second dielectric layer ofthe second circuit structure, an additional dielectric layer includingnetworks of electrical connections selectively linking said electricalconnections and outer electrical contacts of an outer face of theadditional dielectric layer.

The method can comprise: mounting a third circuit structure above theadditional dielectric layer of the second circuit structure, by linkingelectronic circuit component of this third circuit structure to saidnetworks of electrical connections via said outer electrical contacts.

The conductive layer can be made of doped polysilicon and the electricalinsulation rings can be obtained by oxidation of the portions of thislayer, adjacent to said holes.

The oxidation can be obtained by thermal or plasma oxidation.

BRIEF DESCRIPTION OF THE DRAWINGS

An electronic IC device including optical circuit components andelectronic circuit component will now be described by way ofnon-limiting exemplary embodiment, illustrated by the drawings in which:

FIG. 1 shows a cross section of an electronic IC device; and

FIGS. 2-7 show steps of fabrication of the electronic IC device of FIG.1 .

DETAILED DESCRIPTION

According to an embodiment illustrated in FIG. 1 , an electronicintegrated circuit (IC) device 1, or electronic IC chip, comprises aplurality of adjacent zones of pixels 2.

The electronic IC device 1 comprises a first circuit structure 3 whichcomprises a substrate layer 4, made of silicon, which has an outer rearface 5 and a front face 6 opposite this rear face 5.

The front face 6 of the substrate layer 4 is provided, in the zones ofpixels 2, with integrated optical circuit component 7 which aresensitive to the light passing through the rear face 4 so as to deliverelectrical signals as a function of the light.

The first circuit structure 3 comprises, above the front face 6, adielectric encapsulation layer 8, for example made of silicon oxide,which has a front mounting face 9.

The electronic IC device 1 comprises a second circuit structure 10 whichcomprises a local substrate layer 11, for example made of silicon, whichhas a front face 12 and a rear face 13 on the side of the first circuitstructure 3.

Between the rear face 13 of the substrate layer 11 and the mounting face9 of the first circuit structure 3, the second circuit structure 10comprises a dielectric layer 14 above the rear face 13 of the substratelayer 11, then an intermediate electrically-conductive layer 15, orground plane, above the dielectric layer 14, then a dielectric layer 16above the conductive layer 14, this dielectric layer 16 having a rearmounting face 17 attached to the front mounting face 9 of the firstcircuit structure 3.

The dielectric layers 14 and 16 are, for example, made of silicon oxideand the conductive layer 15, or ground plane, is, for example, made ofdoped polysilicon.

The front face 12 of the substrate layer 11 is provided, in the zones ofpixels 2, with integrated electronic circuit components 18, includingtransistors, formed on local portions of the substrate layer 11, thissubstrate layer 11 having openings 19.

The result of the above is that the conductive layer 15 extends betweenand at a distance from the optical circuit components 7 and theelectronic circuit components 18.

The second circuit structure 10 comprises, above the front face 12 ofthe substrate layer 11, a dielectric encapsulation layer 20, for examplemade of silicon oxide, this dielectric layer 20 filling the openings 19to the dielectric layer 14 and having a front face 21.

The electronic IC device 1 comprises, in the zones of pixels 2, aplurality of electrical connections 22 which are formed in holes 23which extend between the front face 21 of the dielectric layer 20 andfront electrical contacts 24 of the electronic circuit component 7 ofthe first circuit structure 3 and which pass through the dielectriclayer 20, through and at a distance from the flanks of the openings 19of the substrate layer 11, the dielectric layer 16, the conductive layer15 and the dielectric layer 8.

The electrical connections 22 are electrically insulated from theconductive layer 15 by virtue of electrical insulation rings 25 whichsurround the electrical connections 22 and which are distinct from thedielectric layers 14 and 16. The electrical insulation rings 25 areformed in the thickness of the conductive layer 15.

In particular, the electrical insulation rings 25 are composed ofreduced local annular portions of the conductive layer 15 surroundingthe electrical connections 22, these local portions being rendereddielectric.

For example, where the conductive layer 15 is made of doped polysilicon,the electrical insulation rings 25 are made of oxidized dopedpolysilicon.

The electronic IC device 1 comprises, in the zones of pixels 2, aplurality of electrical connections 26 which are formed in holes 27which extend between the front face 21 of the dielectric layer 20 andthe front electrical contacts 28 of the electronic circuit components 18of the second circuit structure 3 and which pass through the dielectriclayer 20.

The second circuit structure 10 of the electronic IC device 1 comprisesa front dielectric layer 29 above the front face 21 of the dielectriclayer 20.

The front dielectric layer 29 includes, in the zones of pixels 2,networks of electrical connections 30 configured so as to selectivelylink the electrical connections 22 and 25 and outer front contacts 31formed in a front face 32 of the front dielectric layer 29.

More particularly, the networks of electrical connections 30 areconfigured so as to ensure, in the zones of pixels 2, electrical linksbetween the optical circuit components 7 and the electronic circuitcomponents 18, which convert the electrical signals from the opticalcircuit components 7, and electrical links between the electroniccircuit components 18 and the front electrical contacts 31 to deliverthe converted electrical signals.

Moreover, the conductive layer 15 can be linked to the ground byelectrical connections, not represented, formed in holes passing throughthe dielectric layers 11, 14 and 20 and linked to the networks ofelectrical connections 30.

The electronic IC device further comprises a third circuit structure 33,not detailed in the figure, which is attached to the front face 33 ofthe layer 29 of the second circuit structure 10.

This third circuit structure 33 comprises electronic circuit components,notably transistors, which are linked to the electrical contacts 31 andwhich are capable of processing the electrical signals coming fromelectronic circuit components 18 of the second circuit structure 10 viathe networks of electrical connections 30.

The electronic IC device 1 can be fabricated according to the followingsteps.

As illustrated in FIG. 2 , on the one hand, there is completed the firstcircuit structure 3, the dielectric layer 8 being integral.Advantageously, the substrate layer 4 is thick.

On the other hand, there is a completed part 10A of the second circuitstructure 10, this completed part 10A comprising the integral substratelayer 20, not provided with the openings 19 and not provided with theelectronic circuit components 18, the integral dielectric layer 14, theintegral conductive layer 15 and the integral dielectric layer 16.

The adjective “integral” means that the abovementioned layers are notprovided with any holes.

The first circuit structure 3 is assembled by attaching the mountingface 9 of the dielectric layer 8 and the mounting face 17 of thedielectric layer 16.

After which, as illustrated in FIG. 3 , the electronic circuitcomponents 18 are produced on the front face 12 of the substrate layer11, and the openings 19 are produced through the substrate layer 11, inthat order, or in the other order.

After which, as illustrated in FIG. 4 , the dielectric layer 20 isproduced above the substrate layer 11, this layer 20 filling theopenings 19 of the substrate layer 11 to the dielectric layer 14.

After which, as illustrated in FIG. 5 , the holes 23 and 27 are producedby etching.

Then, as illustrated in FIG. 6 , the portions of the conductive layer 15adjacent to the holes 23 are transformed into a dielectric material, viathe holes 23.

For example, where the conductive layer 15 is made of doped polysilicon,an oxidation gas is introduced into the holes 23 so that, by thermal orplasma oxidation, the annular portions surrounding the holes 23 of theoxidation layer 15 are transformed into dielectric oxidized dopedpolysilicon and form the electrical insulation rings 25.

After which, as illustrated in FIG. 7 , the holes 23 and 27 are filledwith an electrically-conductive material so as to produce the electricalconnections 22 and 26, this material being, for example, tungsten.

According to a variant embodiment, on the one hand the holes 23 and theelectrical connections 22 filling them and on the other hand the holes27 and the electrical connections 26 filling them can be producedaccording to distinct steps.

After which, the dielectric layer 29 provided with the networks ofelectrical connections 30 is produced.

The electronic IC device 1 illustrated in FIG. 1 is then obtained,without the third circuit structure 33.

After which, the third circuit structure 33 is assembled on the face 32of the second circuit structure 10.

After which, the back of the substrate layer 4 of the first circuitstructure 3 is thinned, so that the light appropriately reaches theoptical circuit components 7.

The electronic IC device 1 can be fabricated by implementing the meansand the procedures used routinely in the field of microelectronics.

As an indication, the thicknesses of the different layers can be asfollows.

The thickness of the substrate layer 4 can be approximately fourmicrometers.

The thickness of the dielectric layer 8 can be approximately two hundrednanometers.

The thickness of the substrate layer 11 can be approximately twenty-fivenanometers.

The thickness of the dielectric layer 14 can be approximatelytwenty-five nanometers.

The thickness of the conductive layer 15 can be approximately thirtynanometers.

The thickness of the dielectric layer 16 can be approximately twentynanometers.

The thickness of the dielectric layer 20 can be approximately threehundred nanometers.

The thickness of the dielectric layer 29 including the networks ofelectrical connections 30 can be approximately three micrometers.

The result of the above is that the electronic IC device 1 obtains thefollowing advantages.

The conductive layer 15 forming a ground plane, because of its largesurface area going as far as short distances from the electricalconnections 22, effectively prevents any capacitive coupling between theoptical circuit components 7 and the electronic circuit components 18.

The electrical connections 22 linking the optical circuit components 7and the electronic circuit components 18 are produced through only thedielectric layers 8, 14 and 20 and the conductive layer 15.

The electrical insulation between the conductive layer 15 and theelectrical connections 22, via the electrical insulation rings 25resulting from a local transformation of the conductive layer 15 intoreduced dielectric portions, is produced simply via the holes 23, beforethe filling of these holes 13 to obtain the electrical connections 22.

1. A method for manufacturing an electronic integrated circuit (IC)device, comprising: fabricating a first circuit structure comprising, insuccession, between an outer face and a mounting face: a substrate layerprovided on the side of the mounting face with light-sensitive opticalcircuit components and a dielectric layer; fabricating, separately fromthe first circuit structure, a part of a second circuit structurecomprising, in succession, between a mounting face and a front face: afirst dielectric layer including an intermediate electrically-conductivelayer, and a local substrate layer; assembling the first circuitstructure and said part of the second circuit structure by attaching themounting face of the first circuit structure and the mounting face ofthe second circuit structure; producing through-openings which extendthrough the local substrate layer of the second circuit structure;producing a second dielectric layer above the local substrate layer ofthe second circuit structure, wherein the second dielectric layer fillssaid through-openings; producing holes extending through the first andsecond dielectric layers and which pass through said through-openings inthe local substrate layer of the second circuit structure and at adistance from edges of the through-openings, and also pass through theintermediate electrically-conductive layer and further pass through thedielectric layer of the first circuit structure, said holes extending toreach electrical contacts of the light-sensitive optical circuitcomponents of the first circuit structure; transforming portions of theintermediate electrically-conductive layer, located adjacent to theholes, to produce electrical insulation rings surrounding the holes; andfilling said holes with an electrically-conductive material so as toform electrical connections linked to the electrical contacts of thelight-sensitive optical circuit components of the first circuitstructure.
 2. The method according to claim 1, further comprisingproducing an electronic circuit component on the local substrate layerat said front face of the second circuit structure.
 3. The methodaccording to claim 2, further comprising: producing holes through thesecond dielectric layer of the second circuit structure to reachelectrical contacts of the electronic circuit component; and filling theholes with an electrically-conductive material so as to form electricalconnections linked to the electrical contacts of the electronic circuitcomponent of the second circuit structure.
 4. The method according toclaim 1, further comprising: producing, above the second dielectriclayer of the second circuit structure, an additional dielectric layerincluding networks of electrical connections selectively linking saidelectrical connections and outer electrical contacts of an outer face ofthe additional dielectric layer.
 5. The method according to claim 4,further comprising: mounting a third circuit structure above theadditional dielectric layer of the second circuit structure; and linkingan electronic circuit component of the third circuit structure to saidnetworks of electrical connections via said outer electrical contacts.6. The method according to claim 1, wherein transforming comprisesapplying a material transformation process to said portions of theintermediate electrically-conductive layer through said holes.
 7. Themethod according to claim 6, wherein the intermediateelectrically-conductive layer is made of doped polysilicon and whereinthe material transformation process comprises an oxidation of saidportions of the intermediate electrically-conductive layer.
 8. Themethod according to claim 7, wherein the oxidation comprises a thermaloxidation through said holes.
 9. The method according to claim 7,wherein the oxidation comprises a plasma oxidation through said holes.10. A method for manufacturing an electronic integrated circuit (IC)device, comprising: fabricating a circuit structure comprising, insuccession, between an outer face and a front face, a substrate layerincluding light-sensitive optical circuit components, a first dielectriclayer, an intermediate electrically-conductive layer, a seconddielectric layer, and a local substrate layer; producingthrough-openings which extend through the local substrate layer;producing a third dielectric layer above the local substrate layer,wherein the third dielectric layer fills said through-openings;producing holes extending through the first, second and third dielectriclayers and which pass through said through-openings in the localsubstrate layer at a distance from edges of the through-openings, andalso pass through the intermediate electrically-conductive layer, saidholes extending to reach electrical contacts of the light-sensitiveoptical circuit components; transforming portions of the intermediateelectrically-conductive layer, located adjacent to the holes, to produceelectrical insulation rings surrounding the holes; and filling saidholes with an electrically-conductive material so as to form electricalconnections linked to the electrical contacts of the light-sensitiveoptical circuit components.
 11. The method according to claim 10,further comprising producing an electronic circuit component on thelocal substrate layer at said front face.
 12. The method according toclaim 11, further comprising: producing holes through the seconddielectric layer to reach electrical contacts of the electronic circuitcomponent; and filling the holes with an electrically-conductivematerial so as to form electrical connections linked to the electricalcontacts of the electronic circuit component.
 13. The method accordingto claim 10, further comprising: producing, above the third dielectriclayer, an additional dielectric layer including networks of electricalconnections selectively linking said electrical connections and outerelectrical contacts of an outer face of the additional dielectric layer.14. The method according to claim 13, further comprising: mounting afurther circuit structure above the additional dielectric layer; andlinking an electronic circuit component of the further circuit structureto said networks of electrical connections via said outer electricalcontacts.
 15. The method according to claim 10, wherein transformingcomprises applying a material transformation process to said portions ofthe intermediate electrically-conductive layer through said holes. 16.The method according to claim 15, wherein the intermediateelectrically-conductive layer is made of doped polysilicon and whereinthe material transformation process comprises an oxidation of saidportions of the intermediate electrically-conductive layer.
 17. Themethod according to claim 16, wherein the oxidation comprises a thermaloxidation through said holes.
 18. The method according to claim 16,wherein the oxidation comprises a plasma oxidation through said holes.